Serial dependence persists longer for imaginary versus real stimuli

Perceptual reports across a range of tasks exhibit an attraction towards recent stimuli. This phenomenon is termed serial dependence and has been proposed to arise from internal priors of a natural world that changes slowly over time. Efforts to identify the origin of serial dependance have shown that stimulus strength, attention, working memory, and motor responses can all impact the magnitude (and direction) of serial biases. Thus, rather than a single mechanism, serial dependence may arise due to a canonical prior for stability present across distinct circuits supporting different cognitive functions. To test this hypothesis, we systematically manipulated visual stimulation, attention, and motor output across trials to assess their respective influences on serial dependence. In addition to a standard spatial working memory task, we utilized a novel “compass” memory task that used abstract, semantic cues to indicate the remembered location, critically allowing us to induce a spatial memory in the absence of a physically corresponding stimulus. We found robust and generalizable attractive biases towards past responses regardless of the presence/absence of visual stimulation. Biases were stronger for visual stimuli but persisted longer for imagined stimuli, suggesting the operation of a common prior in distinct circuits.